The carbon trading mechanism is an important measure for airlines to achieve low-carbon emissions reduction and reduce operating costs, and flight scheduling and fleet assignment are key factors affecting airlines' carbon emissions and operating profits. This article comprehensively considers both aspects. Firstly, based on the characteristics of different operational stages of the aircraft, two carbon emission calculation models were constructed for each stage: during the Land and Take off (LTO) stage, a CO2 emission calculation model was established according to the fuel standards of the aircraft engine of International Civil Aviation Organization (ICAO); Establish a multiple regression prediction model based on multiple influencing factors during the cruise phase. On this basis, with the goal of maximizing airline revenue, a mixed integer linear optimization model is established for flight scheduling and fleet assignment, which is divided into two scenarios: considering carbon trading costs and not considering carbon trading costs, to optimize the route network. Select the actual operational data of a certain airline in 2019 for verification, the calculation results show that the proposed full process carbon emission calculation model has high accuracy, with a mean error of 1.64%. In the scenario of not considering carbon trading costs, the increase in operating income reached 7.26%; In the scenario of considering carbon trading costs, it is possible to significantly reduce carbon emission costs by 4.71%, while increasing operating profits by 3.28%, achieving dual effect of achieving low-carbon emission reduction optimization and operational revenue improvement for airlines can provide theoretical guidance for their operational strategies.